The present invention generally relates to wireless communication networks, and particularly relates to packet data flow control within the network.
A typical wireless communication network that supports packet data connections includes some type of packet network that interfaces mobile stations supported by a radio access network with one or more packet data networks, such as the Internet. Details vary depending on the equipment vendor and the relevant communication network standards (e.g., cdma2000, W-CDMA, etc.), but a basic scheme depends on the use of a packet router that routes packet data to and from the radio access network. In cdma2000 network standards, this packet router is referred to as a Packet Data Serving Node (PDSN).
In turn, the radio access network includes a radio-to-packet interface entity that transfers packet data incoming from the PDSN to an associated Base Station (BS) that provides radio links to one or more mobile stations. The interface entity further transfers packet data incoming from the mobile stations (via the BS) to the PDSN. In cdma2000 network standards, the interface entity is referred to as a Packet Control Function (PCF).
The first time a mobile station connects to the PDSN it establishes a packet data connection with it. Once the mobile station has made this connection to the PDSN, the mobile station remains logically connected to it—subject to time-outs and other resource controls—even though user traffic links between the PCF and BS and radio links to the mobile station may be set up and torn down as needed to support the mobile station's data activity. Processing efficiency and improved packet data service is gained by retaining the mobile station's packet data connection within the network even when none of the more “precious” radio link resources are allocated to the mobile station.
With the above connection scheme, the PDSN transfers incoming packet data for a given mobile station to the PCF on the corresponding data connection(s) maintained between the PDSN and the PCF. The PCF is responsible for managing the packet-data “states” of the data-connected mobile stations by tracking whether each mobile station is “active” or “dormant.” Here, the term dormant broadly connotes a mobile station having no allocated radio links and no allocated PCF-to-BS links to support packet data transfer, although radio links still can be allocated for other services, such as voice calls
Because the typical PDSN or like entity has no knowledge regarding the actual availability of its logically connected mobile stations, it simply transfers incoming packet data to the PCF for delivery to the individually targeted mobile stations. The PCF is left to determine whether a targeted mobile station is active or dormant and, if dormant, to undertake operations to establish radio links to it for delivery of the data. Buffering the transferred data while waiting for the radio connection thus represents a key PCF function.
If a radio connection cannot be established for the mobile station, the PCF is unable to deliver the data transferred to it from the PDSN. However, because the PDSN is unaware of the radio connection status or, in general, the availability of the mobile station, that failure often does not prevent the PDSN from continuing its transfer of data to the PCF for delivery to the unavailable mobile station. Such repeated transfers can lead to network inefficiencies by requiring the PCF to repeat its buffering and delivery attempt operations for a mobile station that is at least temporarily unavailable. Further, such failed delivery attempts can lead to billing/accounting errors in terms of unrecognized data delivery failures.